Muffler

ABSTRACT

A muffler particularly suited to motorcycles includes a cylindrical casing incorporating a tube assembly comprised of long and short tubes circumferentially spaced about an inner wall portion of the casing. A deflector plate is positioned in the casing to receive and deflect backwardly gases passing through the short tubes. The gases are then caused to reverse again and pass through the long tubes which communicate with the other side of the deflector plate. The cylindrical casing itself includes an annular internal ridge close to the reversal point of the gases to trap carbon particles and thus prevent sparks. Gases exiting from the long pipes then pass through a baffle arrangement at the exit end of the cylindrical casing. The design results in substantial muffling of noise carried along the route of the gases through the muffler.

United States Patent [191 Foster et a1.

[ 1 Jan. 22, 1974 1 MUFFLER [22] Filed: May 10, 1973 [21] Appl. No.: 358,889

Related US. Application Data [63] Continuation-in-part of Ser. No. 282,493, Aug. 21,

1971, Pat. NO. 3,754,620.

Primary ExaminerRichard B. Wilkinson Assistant ExaminerVit W. Miska Attorney, Agent, or Firm-Pastoriza and Kelly; Ralph B. Pastoriza, Esq.

[ 57] ABSTRACT A muffler particularly suited to motorcycles includes a cylindrical casing incorporating a tube assembly comprised of long and short tubes circumferentially spaced about an inner wall portion of the casing. A deflector plate is positioned in the casing to receive and deflect backwardly gases passing through the short tubes. The gases are then caused to reverse again and pass through the long tubes which communicate with the other side of the deflector plate. The cylindrical casing itself includes an annular internal ridge close to the reversalpoint of the gases to trap carbon particles and thus prevent sparks. Gases exiting from the long pipes then pass through a baffle arrangement at the exit end of the cylindrical casing. The design results in substantial muffling of noise carried along the route of the gases through the muffler.

1 Claim, 5 Drawing Figures MUFFLER This application is a continuation in part of our copending application Ser. No. 282,493 filed Aug. 21, 1971, now U.S. Pat. No. 3,754,620 and entitled MUF- FLER.

This invention relates to mufflers and in its preferred embodiment particularly to motorcycle mufflers.

BACKGROUND OF THE INVENTION Noise silencing mufflers are well known in the art and take on a variety of forms. Some types of mufflers incorporate sound absorbing material while others incorporate circuitous passages effectively lengthening the path of exhaust gases as from a vehicle combustion engine to thereby effect noise attenuation.

In all such designs as the foregoing, it is desirable to minimize back pressure in the exhaust system. It is also important to arrest sparks. In the case of smaller vehicles and particularly motorcylces, a third consideration is the physical size of the muffler. Clearly it would be desirable to minimize the muffler dimensions as much as possible without sacrificing efficiency in noise attenuation.

BRIEF DESCRIPTION OF THE PRESENT INVENTION With the foregoing in mind, the present invention contemplates an improved muffler construction which provides substantial noise attentuation without undue creation of back pressures in the exhaust line. Further, the design is such as to minimize the risk of sparks at the outlet of the muffler without the necessity of a conventional typespark arrester, although the structure is such that a simple spark arrester can readily be accomodated. Finally, the overall structural relationship of the components is such as to minimize the physical size of the muffler thereby making it ideal for use on smaller vehicles and motorcylces.

Briefly, the muffler comprises a cylindrical casing and a tube assembly within the casing. The tube assembly includes a plurality of open ended long tubes circumferentially spaced about an inner wall portion of the casing with the tube axes parallel to the axis of the casing. A plurality of short open ended tubes, in turn, is disposed alternately between the long tubes circumferentially about the inner wall portion of the casing. Deflector means positioned in the casing guide gases passing into the casing back through the short tubes and thence forward through the long tubes towards the outlet end of the casing.

In the preferred embodiment, the deflector means includes a funnel shaped deflector in the entrance end of the casing terminating in a cylindrical nose portion coaxial with the axis of the casing. The long and short tubes have first ends disposed in the annular space between the nose portion and interior portion of the casing and extended second ends passing beyond the end of the nose portion. The long tubes extend for a greater distance than the short tubes. A deflector plate spaced from the extended second ends of the short tubes serves to deflect gases passing through the nose of the funnel shaped deflector back through the short tubes. The second extended ends of the long tubes communicate with the other side of the deflector plate.

In the foregoing preferred embodiment, the outlet end of the muffler incorporates a closed end cylindrical pipe with a cooperating short pipe designed to accomodate a spark arrester if desired and to further define a baffling for exhaust gases.

The component parts are incorporated in the cylindrical casing. This casing itself includes an annular internal ridge surrounding the funnel shaped deflector for trapping carbon particles.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be had by now referring to a preferred embodiment thereof as illustrated in the accompanying drawings in which:

FIG. I is a side cross-sectional view of the overall muffler with certain interior portions being shown in fragmentary view;

FIG. 2 is a transverse cross-section taken in the direc tion of the arrows 22 of FIG. 1;

FIG. 3 is a transverse cross-section taken in the direction of the arrows 3-3 of FIG. 1;

FIG. 4 is a transverse cross-section taken in the direction of the arrows 44 of FIG. 1; and,

FIG. 5 is a transverse cross-section taken in the direction of the arrows 5-5 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 the muffler includes an elongated outer cylindrical casing I0 open at each end. The right hand portion of the outer casing 10 is arranged to be secured in an exhaust line to receive exhaust gases as indicated by the arrows.

As shown, this right hand end or inlet end includes a funnel shaped deflector 11 having a mouth receiving gases and sealed at its periphery to the inner annular wall of the inlet and of the casing. The funnel tapers down into a coaxially aligned cylindrical nose l2.

Positioned within the annular space defined between the exterior of the nose portion 12 and an interior wall portion of the outer casing 10 are a plurality of long and short tubes. Two of the short tubes are indicated in full lines at 13 and 14, the far ends of the tubes extending beyond the end of the nose but terminting short of a deflector plate 15. Two of the long tubes are shown at 16 and 17 also positioned in the annular space between the nose 12 and interior wall portion of the casing 10. The long tubes extend beyond the nose l2 and beyond the ends of the short tubes 13 and 14 to communicate with the other side of the deflector plate 15. The short tubes are alternately disposed circumferentially with the long tubes, the axes of both short and long tubes running parallel to the axis of the cylindrical casing 10. The tube assembly made up of the short and long tubes and the deflector plate function to guide gases passing from the nose portion 12 back through the extended ends of the short tubes to the annular space between the exterior of the funnel shaped deflector 11 and interior of the surrounding casing, the gases then reversing direction again to pass through the long tubes to the other side of the deflector 15.

In accord with an important feature of this invention, there is provided an internal annular ridge l0 surrounding the funnel shaped deflector 11. This ridge may be provided by forming an annular exterior groove about the casing as shown.

The outlet end of the casing 10 includes a spark arrester 18 in the form of a cylindrical screen. This spark arrester surrounds a closed end cylindrical pipe 19 coaxially positioned in the outlet end portion of the outer casing. The closed end cylindrical pipe 19 is of smaller diameter than the casing and the wall includes openings 20. The closed end 21 of the cylindrical pipe 19 faces gases passing from the long tubes, these gases being guided in the annular space between the exterior of the closed end cylindrical pipe 19 and interior of the outlet end portion of the casing 10 in a manner such that the gases will pass through the spark arrester screen 18 and various openings 20.

The open end of the cylindrical pipe 15) turns inwardly to define a short pipe 22 terminating short of the closed end 21 to thereby define a baffle for the gases passing through the side wall openings 20. These gases will pass back along the exterior of the short pipe 22 and thence forwardly through the short pipe out of the outlet end of the casing all as indicated by the arrows.

FIG. 2 illustrates the tube assembly comprised of the short and long tubes in greater detail. It will be noted in the particular embodiment illustrated that there are actually provided four short tubes l3, 14, 23 and 24. Similarly, there are provided four long tubes l6, 17, 25 and 26, the long and short tubes being alternately circumferentially positioned as illustrated With reference to the cross-section of FIG. 3 taken to the left of the deflector 15 of FIG. I, it will be noted that only the long tubes 16, 17, 25 and 26 can pass gases beyond the deflector plate 15, gases on the other side of the deflector plate 15 being deflected through the short tubes as described in FIG. I.

In the cross-section of FIG. 4, the right hand ends of the short and long tubes; that is, the ends opposite to the extended ends of the tubes are mounted in a support plate 27 which may be in the shape of a washer having suitable openings for these ends of the various tubes, the central opening of the washer surrounding the cylindrical nose portion 12 of the funnel shaped deflector 11.

Referring lastly to the cross-section of FIG. taken through the closed end cylindrical pipe 19, the'sur rounding spark arrester screen 18 is shown. It should be understood, however, that the circuitous path which the gases are caused to follow as a consequence of the tube assembly and closed end cylindrical pipe configuration is in many instances sufficient that no sparks will exit from the outlet end of the casing. In such instances, the spark arrester screen 18 can be eliminated. However, should sparks cause any problems, it is easy to incorporate the annular screen 18 about the closed end cylindrical pipe 21.

OPERATION In operation, the outer cylindrical casing has its right hand end connected to the exhaust gas outlet of the combustion engine with which the muffler is to be used. Exhaust gases will then pass into the open mouth of the funnel shaped deflector 1 l, the decreasing crosssectional area resulting in a speeding up of the gas flow by a venturi effect. The gases passing from the nose l2 strike the deflector plate as described and pass through the extended ends of the short tubes 13 and 14 as viewed in FIG. 1 into the annular chamber defined between the exterior of the funnel deflector II. and

inner cylindrical wall of the casing 10. The internal annular ridge 10' at this point traps carbon particles in the gas stream and thus prevents sparks from passing through the long tubes to an open chamber to the left of the deflector plate 15.

It should be noted that the large open area to the left of the deflector 15 also serves to trap sparks and the like so that, as also mentioned, the spark arrester screen I8 is not mandatory.

From the enlarged chamber area to the left of the deflector plate IS, the gases pass over the exterior of the closed end cylindrical pipe I9 and then through the openings 20 to pass back towards the closed end 21 and thence out through the short pipe 22.

The two double reversals of gas direction flow as caused by the tube assembly and the closed end cylindrical pipe configuration, respectively, result in highly efficient noise attenuation and in actual tests, it has been found that a substantial improvement exists as a consequence of the present design over prior art mufflers of corresponding size.

What is claimed is: I

l. A muffler comprising:

a. an elongated outer cylindrical casing open at each end;

b. a funnel shaped deflector in the casing having a mouth receiving gases and sealed at its periphery to the inner annular wall of the inlet end of the casing, the funnel tapering down into a coaxially aligned cylindrical nose within the casing; v

c. a tube assembly comprising a plurality of long open ended tubes with their axes parallel to the axis of the casing spaced circumfereneitally about the annular space between the nose and inner cylindrical wall of the casing and extending beyond the nose, and a plurality of short open ended tubes spaced alternately with the long tubes in said annular space extending beyond the nose but terminating short of the long tubes;

(1. a deflector plate receiving the extended ends of the long tubes to support the same, said deflector plate deflecting gases from the nose back through the extended ends of the short tubes to the annular space between the exterior of the funnel shaped deflector and interior of the surrounding casing, said interior of the annular casing surrounding the funnel shaped deflector having an internal annular ridge for trapping carbon particles from the gas stream, the gases then reversing direction to pass through the long tubes to the other side of the deflector plate; and,

e. a closed end cylindrical pipe coaxially positioned in the outlet end portion of the outer casing smaller than the casing, the closed end facing gases from the long tubes, said cylindrical pipe having openings in its side wall, the open end of the pipe turning inwardly to define a short pipe terminating short of the closed end to thereby define a baffle for gases passing through the side wall openings, the gases then passing back along the exterior of the short pipe and thence forwardly through the short pipe out of the outlet end of said casing, whereby noise carried along the route of the gases is muffler and sparking is inhibited. 

1. A muffler comprising: a. an elongated outer cylindrical casing open at each end; b. a funnel shaped deflector in the casing having a mouth receiving gases and sealed at its periphery to the inner annular wall of the inlet end of the casing, the funnel tapering down into a coaxially aligned cylindrical nose within the casing; c. a tube assembly comprising a plurality of long open ended tubes with their axes parallel to the axis of the casing spaced circumfereneitally about the annular space between the nose and inner cylindrical wall of the casing and extending beyond the nose, and a plurality of short open ended tubes spaced alternately with the long tubes in said annular space extending beyond the nose but terminating short of the long tubes; d. a deflector plate receiving the extended ends of the long tubes to support the same, said deflector plate deflecting gases from the nose back through the extended ends of the short tubes to the annular space between the exterior of the funnel shaped deflector and interior of the surrounding casing, said interior of the annular casing surrounding the funnel shaped deflector having an internal annular ridge for trapping carbon particles from the gas stream, the gases then reversing direction to pass through the long tubes to the other side of the deflector plate; and, e. a closed end cylindrical pipe coaxially positioned in the outlet end portion of the outer casing smaller than the casing, the closed end facing gases from the long tubes, said cylindrical pipe having openings in its side wall, the open end of the pipe turning inwardly to define a short pipe terminating short of the closed end to thereby define a baffle for gases passing through the side wall openings, the gases then passing back along the exterior of the short pipe and thence forwardly through the short pipe out of the outlet end of said casing, whereby noise carried along the route of the gases is muffler and sparking is inhibited. 